Adenosylcobalamin (active B12, mitochondrial)
What it is
One of the two active coenzyme forms of vitamin B12 (the other being methylcobalamin). Adenosylcobalamin is the form required by the mitochondrial enzyme methylmalonyl-CoA mutase and may be the more relevant form for energy and methylmalonic-acid lowering. Often paired with methylcobalamin to cover both methylation and mitochondrial pathways. Particularly relevant in MTHFR variants, vegan diets, and proton-pump-inhibitor users.
Dose
1,000–5,000 mcg adenosylcobalamin daily, ideally sublingual
Time of day & tips
Sublingual delivery bypasses intrinsic-factor dependence — useful in absorption issues; combine with methylcobalamin for full coverage; can turn urine bright pink (harmless).
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